Rear pinion bearing question

[Bruce_MO]

I rebuilt my rear end with all new bearings, races, new 3.54 R &P and have driven it about 130 miles so far; just 5-10 mile trips around the neighborhood. After an approx 5 mile drive the other day, I was under the car and noticed that the rear axle was quite warm in the area where the torque tube bolts to the axle housing (pinion bearing area). So I took out a couple other cars and drove them (they have lots of miles on them), and they were cooler (one had no noticable temp variation with any other part of the diff housing and one had a bit more heat, but quite a bit cooler than my newly rebuilt rear end). When I set up the rear end, I though I got pretty close to "target" on pinion brg drag, but I did it by feel. I worked the pinion gear sleeve with a lot of emery cloth because I knew the repro pinions don't have the proper taper to allow the 1st brg on to be a press fit and the second has less/no interference to set preload. All seemed normal and I'm using 75/25 mix of 600wt and STP.

Should I just drive it easy and assume it'll "wear in" a bit? Thanks

[Kurt in NJ]

Was the bearing preload set before the race was pressed into the banjo housing?

Describe what "feel" the preload was ---2 fingers could turn, 2 hands could turn ??

Are you using 600w steam cylinder oil, or 600 series of bevel and spur gear lubricant ---and why thickner additive?? ---I am not trying t start another oil war, but too thick of oil will create higher temps too

[H. L. Chauvin]

Hi Bruce,

My guess is that for others who may want to try a recommended "feel" on inch-pound torque for the "first time" in the future, "feel" varies drastically from person to person -- e.g., I went to a party whereby my friend's mother tried unsuccessfully to get ice from her freezer with a frozen door gasket -- several tried to pull on the door & it would not budge.

One guy later tried -- have no idea what his "feel" range or level was, but after he pulled, he had this dumbfounded look after he was holding a freezer door in his hand after the (2) door hinges broke off.

Mr. Steve Becker at Bert's or Mr. Tom Endy may be able to suggest a recommendation for your situation..

[Tom Endy]

If you are generating excessive heat in the banjo it is because you have either the two pinion bearings, the two carrier bearing, or all four set up too close. When rebuilding the rear axle assembly you would want to have a nominal 20 in lbs of rotational torque on both assemblies.

Tom Endy

[Tom Wesenberg]

I saw a rear end where the builder mixed up inch pounds with foot pounds, which would make it 12 times tighter. Not good.

I use the temp gun on my 28 rear end a few years ago after a 20 miles drive, and it wasn't more than a few degrees warmer than the air around it.

[Bruce_MO]

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The new race was pressed into the housing before I assembled things. The amount of preload I would describe as a bit more than "slight drag"... it did not require any significant force to turn and one hand could turn it with a small amount of resistance.

[Mitch//pa]

sounds to me like its to tight. i remove the end play and then a hair smidget more which is hardly any drag at all.. to tight youll smoke the bearings in not time and also regarding your post and the step on the pinion for the inner bearing the good usa gears have that machined in, cheaper chinese do not. i have heard of off shore gears being resold as usa be careful who you deal with..

[Cajun]

I had a similar issue. The temperature as measured by Fluke IR meter was about 152 F. I talked with a professional rebuilder and he saw no issue with this on a newly rebuilt rear end.

I check a modern truck and had similar temperatures.

I decided to drive it and so far (1500 miles) all is well.

[Jon]

Same here, rebuilt mine and after the first short ride reached under and was hot to the touch. Called one of the guys in our club and he said if I was confident in my rebuild to just drive it. That was 6 yrs. and 16,000 miles ago. Makes no noise and no leaks. Never checked the temp after that. If I remember I will check it after the next drive.

[Tom Endy]

I just recently rebuilt a rear axle assembly for a local restoration shop. The shop owner told me the car, a very nice 30 coupe, has a loud howl coming from the rear of the car whenever he let off on the gas. The owner of the car restored it in the 1960's when he was a young man and he still has it. He is somewhat older now.

What I found was that when the car was restored the two large pinion nuts had been tightened down tight with no thought to pre-load. The bearings were locked, however, Henry's 40 horses broke things loose and for the last fifty years the drive shaft and the pinion gear assembly have been rotating inside the banjo flange without the aid of bearings. I imagine the banjo was extremely hot for the first few hundred miles.

The banjo flange was completely wallowed out where the double race presses in. I had to replace the banjo. A new set of bearings and proper pre-load adjustments and it was back on the road nice and quiet.

This is certainly a testimony to the ruggedness of the Model A Ford. They will run no matter how bad they are molested.

Tom Endy

[Mitch//pa]

i hear ya tom on that these cars can run even with things like that wrong. amazing isnt it;;;;
try that in a modern car that sucker wont go far before it boomerangs
i still stick to my above post that its to tight

[Tom Endy]

Originally Posted by Mitch//pa

i hear ya tom on that these cars can run even with things like that wrong. amazing isnt it;;;;
i still stick to my above post that its to tight

The majority of the rear axle assemblies I rebuild I find that one or both carrier bearings have "spun" on the mounting hub. This is caused by the last person putting it together not understanding carrier pre-load requirements and just put it together with a banjo gasket on each side. The proper way to set carrier pre-load is by the selection of the total number and thickness of banjo gaskets used in the assembly process.

I maintain a stock of knurled carriers and have to replace carriers in 3 out of 4 jobs that come in house.

Establishing carrier pre-load is a tedious trial and error process that may require putting it together and taking it apart a number of times until the pre-load is correct. It is difficult to hit 20 in lbs dead on. I am satisfied when carrier pre-load is between 15 and 22.

Once the total number and thickness of banjo gaskets are determined they are later distributed to either side of the banjo when the backlash adjustment is made.

If the banjo is excessively hot after a rear axle assembly is rebuilt it is because either of the two pre-loads (or both) were not properly set.

The advice from the experts is correct. In a few hundred miles it will cool down, when the carrier bearings have spun on their mounts, or the pinion double race has spun in the banjo, or metal is worn away in some other area.

Tom Endy

[Jon]

I hope I'm not one of the experts you are referring to. I had to use your instructions to rebuild mine and I followed them to the letter using an inch pound torque wrench. I had never seen the inside of one before. I just took the car for a 40 minute drive and it started at 67* which was ambient. When I got home temp. of housing was 105* with no hot spots. I had to use all new gears, bearings, and races. The first drive I took after rebuilding housing read 130*. I suspect with all new gears there is a wear in period and that you're going to generate some heat, for how long I don't know. I also know that you're going to generate some heat in any kind of gearbox just by the nature of it. So does anyone know the normal temp. range for a properly rebuilt rear end?

[john charlton]

On the first rear end I did I followed the good books instructions very very carefully . Double checking that 20 inch pounds was spot on. Ran the rear end for a short test on axle stands and my new black paint on the banjo neck began to bubble .I pulled the axle and re did it . I then found by trial and error that the preload should be verified only AFTER the lock nut is tight tight tight. When the lock nut is tightend it loads the threads on the inner nut inwards this is enough to seriously increase the preload .

John in nice evening Suffolk County England.

[Tom Endy]

Originally Posted by john charlton

On the first rear end I did I followed the good books instructions very very carefully . Double checking that 20 inch pounds was spot on. Ran the rear end for a short test on axle stands and my new black paint on the banjo neck began to bubble .I pulled the axle and re did it . I then found by trial and error that the preload should be verified only AFTER the lock nut is tight tight tight. When the lock nut is tightend it loads the threads on the inner nut inwards this is enough to seriously increase the preload .

John in nice evening Suffolk County England.

John:

You are absolutely correct. When I am setting the pinion pre-load I install the drive shaft (or overdrive stub shaft) first and tighten it down to a nominal 100 ft. lbs. before beginning the pre-load adjustment. I then install the nut assembly and tighten down the first nut until I have about 8-10 in. lbs. of pre-load as read out on a dial indicator torque wrench. I then begin tightening down the second nut in increments and monitor the pre-load. The goal is to have the second nut extremely tight (I hammer the wrench as described in the service bulletins) and the pre-load in the vicinity of 20 in. lbs. Tightening the second nut will increase the pre-load. If it exceeds the desired pre-load I back off on both nuts and tap the end of the drive shaft to move the rear bearing slightly forward and start over.

This is why it is important that the pinion gear sleeve be machined correctly. The originals are such that the first bearing presses on with an interference press fit. The second bearing should install with a snug sliding fit. There is about.0015 difference in diameter on the sleeve where the two bearings fit.

You should be able to feel the transition point with your finger nail. When pressing on the first bearing, as it passes over the area where the second bearing will reside there should be no "crunching" sound that is indicative of a press fit in progress. When it hits the transition point the "crunching" sound should be begin.

Some of the reproduction ring & pinion sets on the market are not machined correctly. The sleeve is all one diameter. It makes it almost impossible to set the pinion pre-load properly.

Walt Bratton told me years ago that he and Snyder are aware of this and the R&P sets they sell are machined correctly. I have found that to be mostly true. You can feel the transition point on the sleeve of their R&P's. However, in some cases I found that both dimensions were not correct. Both were a press fit, one more than the other.

I check all reproduction R&P's very carefully. When I go to press the first bearing on if the "crunching" sound is immediately heard I remove the bearing and machine the surface where the second bearing sits. It does not take much. I have a tool I can clamp the pinion with in a drill press (or a lathe) and with Emory paper I can remove enough metal to get the required snug sliding fit.

Tom Endy